Glenoid cancellous bone strength and modulus

The objectives of this study were to determine the strength and modulus of glenoid cancellous bone, including regional variations. The motivations wer e: to select a suitable bone substitute for standardized testing of glenoid prosthesis loosening, to assist in shoulder prosthesis design and to provi de input data for finite element analyses. Ten glenoids from eight cadavers (mean age, 81) were tested by in situ indentation. Mean strength ranged fr om 6.7 to 17 MPa for then glenoids, the overall mean being 10.3 MPa. Mean E moduli ranged from 67 to 171 MPa for the individual glenoids, the overall mean being 99 MPa. These values are likely at the lower end of what would b e expected for normal bone since strength and modulus decrease with age and the available specimens were older. These values may be appropriate for pr osthesis design, however, since mechanical properties are reduced in rheuma toid arthritic bone. Regional trends were very similar for modulus and stre ngth. The strongest region was postero-superior. The central column, correl ating with the keel position in many glenoid components, was weak-than both the anterior and posterior regions but deeper. A large drop in strength an d modulus below the subchondral layer emphasizes the importance of maintain ing this layer during prosthetic replacement. (C) 1999 Elsevier Science Ltd . All rights reserved.